I think Dyson benefits from the same effect as Apple/Tesla/Beats/etc. Their products are good but their triumph is upselling. Dyson cordless vacuums are like $800+, was your previous one that expensive?
Their tech probably can't be imitated at the moment because they've got it patented up the wazoo. Luckily patents have a sane lifetime and once they expire I'd expect many competitors to show up with similar designs at lower price points and possibly better engineering.
Perhaps, but just like Apple they have a refurbished category where you can get very good deals - and that's on top of them having sales regularly.
I should add that I called Dyson once for my 7 year old wireless vacuum which was having battery problems. They mailed me a replacement completely free of charge. The upselling might be there, but the up-service also seems to be there.